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WarrenS

Sun, Sep 11, 2011 11:14 PM

HP 3456A front panel set up to measure low noise precision references,
Preferable the difference between to two like units

With the input (or difference) to be measured connected to the "Volts"
inputs
0) warm it up for a few hrs or days, especially if you are not using an
external reference voltage.

Select "DC volts"
"Guard button" IN
"Auto Zero" ON
"Filter" OFF
"Auto Range" Selected
"INT" selected
enter-keys "6", "Store", "N DIG DISP" (#9 key)
enter-keys "100", "Store", N Cycles Int" (CHS key)
with Inputs shorted push "Math" "Off" (#0 key)
9a) then push "Math" "Null" (#3 key)

If you have a good external 10 volt reference that is floating, it can be
used by connecting it to the "Ratio Ref" inputs,
Add a Jumper from "Ref Low Input" to "Signal Low input"
and select DC Ratio mode with "Shift" "DC_Volts"

Measure away and have fun
ws

From: John Ackermann N8UR
Subject: [volt-nuts] HP 3456A Setup

Any suggestion on the best settings to use (particularly the PLC
integration and filtering)
to get the best accuracy and resolution for DC measurements with a 3456A
where reading speed isn't an issue?

John

HP 3456A front panel set up to measure low noise precision references, Preferable the difference between to two like units With the input (or difference) to be measured connected to the "Volts" inputs 0) warm it up for a few hrs or days, especially if you are not using an external reference voltage. 1) Select "DC volts" 2) "Guard button" IN 3) "Auto Zero" ON 4) "Filter" OFF 5) "Auto Range" Selected 6) "INT" selected 7) enter-keys "6", "Store", "N DIG DISP" (#9 key) 8) enter-keys "100", "Store", N Cycles Int" (CHS key) 9) with Inputs shorted push "Math" "Off" (#0 key) 9a) then push "Math" "Null" (#3 key) If you have a good external 10 volt reference that is floating, it can be used by connecting it to the "Ratio Ref" inputs, Add a Jumper from "Ref Low Input" to "Signal Low input" and select DC Ratio mode with "Shift" "DC_Volts" Measure away and have fun ws ************************** > From: John Ackermann N8UR > Subject: [volt-nuts] HP 3456A Setup > > Any suggestion on the best settings to use (particularly the PLC > integration and filtering) > to get the best accuracy and resolution for DC measurements with a 3456A > where reading speed isn't an issue? > > John > > > ------------------------------

JA

John Ackermann N8UR

Tue, Sep 13, 2011 4:18 PM

Thanks, Warren! That's very helpful.

John

On 9/11/2011 7:14 PM, WarrenS wrote:

HP 3456A front panel set up to measure low noise precision references,
Preferable the difference between to two like units

With the input (or difference) to be measured connected to the "Volts"
inputs
0) warm it up for a few hrs or days, especially if you are not using an
external reference voltage.

Select "DC volts"
"Guard button" IN
"Auto Zero" ON
"Filter" OFF
"Auto Range" Selected
"INT" selected
enter-keys "6", "Store", "N DIG DISP" (#9 key)
enter-keys "100", "Store", N Cycles Int" (CHS key)
with Inputs shorted push "Math" "Off" (#0 key)
9a) then push "Math" "Null" (#3 key)

If you have a good external 10 volt reference that is floating, it can
be used by connecting it to the "Ratio Ref" inputs,
Add a Jumper from "Ref Low Input" to "Signal Low input"
and select DC Ratio mode with "Shift" "DC_Volts"

Measure away and have fun
ws

From: John Ackermann N8UR
Subject: [volt-nuts] HP 3456A Setup

Any suggestion on the best settings to use (particularly the PLC
integration and filtering)
to get the best accuracy and resolution for DC measurements with a
3456A where reading speed isn't an issue?

John

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Thanks, Warren! That's very helpful. John ---- On 9/11/2011 7:14 PM, WarrenS wrote: > HP 3456A front panel set up to measure low noise precision references, > Preferable the difference between to two like units > > With the input (or difference) to be measured connected to the "Volts" > inputs > 0) warm it up for a few hrs or days, especially if you are not using an > external reference voltage. > > 1) Select "DC volts" > 2) "Guard button" IN > 3) "Auto Zero" ON > 4) "Filter" OFF > 5) "Auto Range" Selected > 6) "INT" selected > 7) enter-keys "6", "Store", "N DIG DISP" (#9 key) > 8) enter-keys "100", "Store", N Cycles Int" (CHS key) > 9) with Inputs shorted push "Math" "Off" (#0 key) > 9a) then push "Math" "Null" (#3 key) > > If you have a good external 10 volt reference that is floating, it can > be used by connecting it to the "Ratio Ref" inputs, > Add a Jumper from "Ref Low Input" to "Signal Low input" > and select DC Ratio mode with "Shift" "DC_Volts" > > Measure away and have fun > ws > > ************************** > >> From: John Ackermann N8UR >> Subject: [volt-nuts] HP 3456A Setup >> >> Any suggestion on the best settings to use (particularly the PLC >> integration and filtering) >> to get the best accuracy and resolution for DC measurements with a >> 3456A where reading speed isn't an issue? >> >> John >> >> >> ------------------------------ > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

CP

Charles P. Steinmetz

Tue, Sep 13, 2011 5:40 PM

Select "DC volts"
"Guard button" IN
"Auto Zero" ON
"Filter" OFF
"Auto Range" Selected
"INT" selected
enter-keys "6", "Store", "N DIG DISP" (#9 key)
enter-keys "100", "Store", N Cycles Int" (CHS key)
with Inputs shorted push "Math" "Off" (#0 key)
9a) then push "Math" "Null" (#3 key)

Note that step 9a turns on what other manufacturers call a "relative"
or "tare" function -- it subtracts a reading taken immediately after
the function is activated from all subsequent readings (untill Math
Null is deactivated). This is handy for cancelling the lead
resistance for resistance measurements, for example. But it is
probably not what you want for normal DC measurements. Instead,
leave Null off and just let Autozero zero out the residual for each
measurement. If the meter has a zero error, you need to correct it
-- not just subtract the zero error you got a while ago from the
current reading.

Regarding the correct connection of the guard terminal, HP
Application Note AN-123 provides a thorough discussion of what to do
and why. Connecting it to the Low input (as by pushing the Guard
button in) is often suitable, but not always.

Best regards,

Charles

>>1) Select "DC volts" >>2) "Guard button" IN >>3) "Auto Zero" ON >>4) "Filter" OFF >>5) "Auto Range" Selected >>6) "INT" selected >>7) enter-keys "6", "Store", "N DIG DISP" (#9 key) >>8) enter-keys "100", "Store", N Cycles Int" (CHS key) >>9) with Inputs shorted push "Math" "Off" (#0 key) >>9a) then push "Math" "Null" (#3 key) Note that step 9a turns on what other manufacturers call a "relative" or "tare" function -- it subtracts a reading taken immediately after the function is activated from all subsequent readings (untill Math Null is deactivated). This is handy for cancelling the lead resistance for resistance measurements, for example. But it is probably not what you want for normal DC measurements. Instead, leave Null off and just let Autozero zero out the residual for each measurement. If the meter has a zero error, you need to correct it -- not just subtract the zero error you got a while ago from the current reading. Regarding the correct connection of the guard terminal, HP Application Note AN-123 provides a thorough discussion of what to do and why. Connecting it to the Low input (as by pushing the Guard button in) is often suitable, but not always. Best regards, Charles

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Re: [volt-nuts] HP 3456A Setup

John